The degree to which visual awareness exists outside focal attention is debated. A recent study (Bronfman et al., 2014, Psychological Science) claimed that perception of a particular ensemble statistic, color diversity, does not rely on limited cognitive mechanisms and is therefore perceived "cost free". In a series of experiments, we tested this claim by combining a modified inattentional blindness paradigm with the same color diversity stimuli used by Bronfman et al. Subjects first carried-out a single task in which they attended to a pre-cued row of letters in a Sperling-like display in order to report letter identities. Color diversity of the letters in the uncued rows was manipulated. Then, on the critical trial, a surprise forced choice recognition test was immediately administered (900ms later) to probe subjects' awareness of color diversity in the unattended rows. Inattentional blindness rates were 78% (experiment 1, N=50), 54% (experiment 2, N=24), and 53% (experiment 3, N=30). These results suggest that conscious perception of color diversity requires attention. Following the critical trial, subjects performed a dual-task on letter identity and color diversity. Letter recall was significantly reduced in the dual-task compared to the single-task, thus demonstrating an attentional cost for perceiving color diversity. We also tested a second ensemble statistic, size diversity, and found similarly high inattentional blindness rates as well as dual-task costs. The present results, along with converging evidence from several recent studies (Cohen et al., 2011; Huang, 2015; Mack & Clarke, 2012; Mack et al., 2015), support the view that conscious perception requires attention, even for easy-to-perceive visual ensemble statistics. In contrast to Bronfman et al.'s (2014) claims, these studies argue that dual-task reportability cannot be cited as evidence of rich conscious perception in the absence of focal attention.